On-line analysis of coal by neutron induced gamma spectrometry

Thermal neutron prompt gamma activation analysis (PGNAA) has proven to be a useful tool for the multi-elemental characterization of coal. As a first step to an on-line analysis system for process control in a coal blending plant we have developed a facility using a Cf-252 neutron source with an actual strength of 1 mg. The prompt gamma rays emitted from the sample are measured with a 22% high purity germanium detector housed in a special horizontally extended cryostate assembly. Analysis of several samples of simulated coals as well as Western Germany coals shows a good spectral response of our system for the elements H, C, Al, Si, S, Cl, Ca, Ti and Fe, whereas the sensitivity for N, K and Na is somewhat lower. This means, that the quantitative determination of the above elements will be possible within 20 minutes. Optimization of the system is continued with a stress on analysis time and detection sensitivity. (author)